The increasing cost and use of energy is a global concern. One unavoidable process that uses energy is the heating of buildings and more specifically the heating of a single area or room within a building. The ability to efficiently heat a room is one way of reducing both the usage and therefore the cost of energy.
One manner to heat only a single room is to utilize a conventional space or room heater. These types of conventional heaters often have advantages over heating systems designed for an entire building. Conventional space heaters create heat within a room without the need to heat additional rooms at the same time. The ability to produce and direct a limited flow of heated air to a desired location reduces the quantity of heat needed by “spot heating” only a single location in the room. In turn “spot heating” reduces the overall needed energy.
Space heaters also eliminate the use of duct work and other permanent structures that are expensive and absorb heat. The heat absorption of duct work etc. contributes to permanent system inefficiencies.
Although conventional electric space heaters have certain advantages over other heating systems they possess several disadvantages as well. The amperage draw associated with a conventional space heater increases the load on the electrical system of the building. In some instances the electrical load generated by a conventional electric space heater can stress the components of the electrical system. For example, if the wall receptacle is old and the contact pressure between the prongs of a plug and the receptacle terminals is not sufficient, this can cause a localized heating problem within the receptacle. Many such receptacles are located behind objects, such for example, furniture, and are not easily visible to the user. The non-visibility of such receptacles impedes the ability of the user to detect problems, should they occur. This localized heating can further create a potential failure of other components in the area and a potential safety compromise.
The use of current sensing circuit interrupters have been utilized in conjunction with electrical appliances for many years. Some conventional types of circuit interruption devices include fuses, circuit breakers (re-settable and non-re-settable), ground fault circuit interrupters (GFCI), appliance leakage circuit interrupters (ALCI), and arc fault circuit interrupters (AFCI).
Conventional fuses and circuit breakers are devices that use amperage to determine the presence of an electrical fault. When excess amperage is detected by conventional fuses and circuit breakers, they respond by interrupting the flow of electric current.
GFCI devices monitor amperage flow and compare amperage flow in and out of an appliance. The GFCI device responds to a pre-determined limit of amperage flow imbalance in and out of an appliance by interrupting the flow of electric current.
AFCI devices monitor voltage and amperage signatures within the branch circuits served by a power distribution panel. Deviations from the normal signatures are monitored by electronic circuits and algorithms to determine if a fault occurs. When a fault is recognized indicating an electrical arc, the flow of electric current is interrupted to the branch circuit.
The above mentioned devices have functional limitations. Conventional current sensing circuit interrupters do not have the ability to directly detect heat build-up due to resistive heating within the appliance, the power supply and/or the interface between the appliance and the power supply. The above mentioned devices will interrupt the flow of power if the amperage/voltage exceeds a pre-determined threshold or increases too rapidly. Unfortunately, resistive heating may build up less rapidly and at current/voltage levels lower than the pre-determined limits of the above mentioned conventional devices, particularly at the interface between the appliance and the power supply. The associated heat buildup may be sufficient to compromise the safety of the appliance or electrical system. The possibility of such a compromise is especially acute on appliances that have a high amperage draw, such as a conventional space heater. This pre-determined limit renders such conventional devices ineffectual for the detection of heat that builds over time and/or levels of heating that are not accompanied by a spike in the current draw on the circuit.